Why do tertiary alkyl halides such as 2-bromo-2-methylpropane undergo substitution primarily via the SN1 mechanism?
Answer and explanation
Correct answer: A. Steric hindrance blocks backside SN2 attack and tertiary carbocations are highly stabilized
Three bulky methyl groups shield the central carbon, preventing backside nucleophilic attack (SN2). However, ionization forms a relatively stable tertiary carbocation (stabilized by hyperconjugation and inductive donation), favoring the two-step SN1 pathway.
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